Here is the full list of all 24 Secret Savings achievements.
Solve the gimmick of billiard.
Find the secret saving for the first time.
Open the lock of back-entrance door.
Shutdown the security system.
Read all diaries.
Solve the gimmick of maintenance room.
Solve the clock gimmick.
Solve the gimmick of room model.
Solve the gimmick of strongbox.
Solve the gimmick of locker.